A space probe stuck in orbit could fall back to Earth as soon as Sunday or Monday, though most experts say the chance that debris will harm anyone on the surface is slim.

And even as the Russian space agency released new forecasts of the probe’s uncontrolled re-entry, other Russian officials dropped dark hints this week that foreign sabotage might be to blame.

Such comments by the Russian space chief, Vladimir Popovkin, were not directed at any single nation, though some interpreted them as being aimed at the United States.

On Tuesday, Popovkin told the Russian daily Izvestia that some of his nation’s spacecraft malfunctions that occurred over other parts of the world, away from Russian tracking facilities, were â€œunexplained.â€

â€œI wouldn’t like to accuse anyone, but today there exists powerful means to influence spacecraft, and their use can’t be excluded,â€ Popovkin said.

The U.S. State Department rejected the assertion Friday.

â€œWe have seen speculation in the Russian media that foreign interference might have contributed to the failures of several recent Russian space missions,â€ said Jamie Mannina of the department’s bureau of arms control verification and compliance, reading from a statement. â€œThat said, we do not believe there is any truth in these reports, but we are interested in hearing further from our Russian counterparts whether there are any specifics to support these claims.â€

The U.S. tried to help the Russians regain control of the craft in the days after the troubled launch, he said.

â€œThe United States and several other nations have provided unprecedented assistance to Russia in its attempts to recover the Phobos-Grunt scientific mission in the days after the launch mishap,â€ he said.

Also Friday, a spokesman for the U.S. Strategic Command agreed with estimates that the probe could re-enter the atmosphere sometime Sunday or Monday â€” with a caveat.

â€œPredictions of re-entry date, time and location can change significantly due to many changing factors, such as solar weather and orientation of the spacecraft,â€ spokesman Rodney Ellison said, also reading from a statement.

The Russian space agencyÂ Roscosmos said the craft could fall over the Indian Ocean north of Madagascar, although that is uncertain.

The agency expressed confidence that highly toxic rocket fuel aboard the craft will burn up on re-entry, and estimated that only about 20 to 30 fragments with a total weight of about 440 pounds would survive the plunge to the surface.

At 14.6 tons, the $170 million Russian spacecraft is one of the heaviest ever to fall back to Earth, but will become the third in the past five months.

A 6-ton NASA satellite fell in September, and a 3-ton German craft in October.

The Russian probe was designed for an ambitious mission: to land on one of two Martian moons, Phobos, collect soil samples, and return them to Earth.